• Analytical Science and Technology
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• v.34 no.6
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• pp.275-283
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• 2021

This study presents the development of cell-based microfluidic chips for the performance of acute eye irritation tests due to chemicals and examined some of their applications. Microfluidic chips were fabricated by photolithography and soft lithography, and they had three compartments with different areas for cell culture. Rabbit corneal epithelial cells were used for the eye irritation test. The death of cells cultured inside the chip was monitored at regular time intervals after treatment with an aqueous solution of chemicals, and the cell death rate constants were calculated based on the viability curve. The performance of the microfluidic chip was verified by examining the effects of cell-cell junctions, cell-substrate adhesion, and initial cell numbers compared to cell death rates. Eye irritation tests were performed at various concentrations of an aqueous solution of sodium dodecyl sulfate (SDS), a standard substance for the eye irritant test. The cells were exposed to the SDS aqueous solution for 300 s, and the resulting eye irritation was assessed by cell viability. Finally, the equation for calculating the toxicity score (TS) was derived based on the weighting factor for each compartment in the chip. The cell-based microfluidic chip developed in this study may be used for eye irritation tests from chemicals used in cosmetics and pharmaceuticals.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.4
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• pp.492-502
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• 1995

This paper describes the relationship between the behavior of the snakehead ( Channa arps) of 44cm long and the environmental noise levels due to the piling work. The experiment is conducted in the aquafarm located near Asan lake, Pyongtaek in 1993. The fish trajectory is obtained by a biotelemetry system in which a pulsed ultrasonic pinger attached onto the dorsal is tracked three dimensionally, and the noise and the vibration levels both in air and in water are measured. The results of this study are as follows: 1) The noise levels in water and in air and the vibration level measured at a distance of 90m from the noise source, increased by 36.5dB $(re\;l{\mu}Pa)$, 2308$(re\;0.0002{\mu}bar)$ and $5.9{\mu}m$ repectively compared to the levers before piling. 2) The highest variation of the swimming speed was observed right after the piling works and the width of variation decreased with the elapsed time. The average speeds of the fish before and during the works were measured as 0.8 times and 1.1 times of the body length, respectively. 3) It is found that the fish escapes into the mud of the aquafarm when a heavy shock wave occurred. Consequently, the heavy shock by the piling works could produce a considerably unfavorable effect to the fish.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1997.11a
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• pp.183-188
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• 1997

안구의 운동은 시각 환경에서의 진행중인 정보처리와 관련된 지각적, 인지적 과정을 밀접히 반영하는 중요한 지표로서, 특히 공간 지각과의 상관은 비교적 명확히 확립되어 있다. 본 연구는 공간지각에 관여하는 안구운동의 특성을 파악하여, 공간지각을 반영하는 안구운동 지표를 개발한다는 목표 아래, 피험자가 느끼는 공간의 확장과 축소의 특성을 이중도약과제(double-step paraeigm)를 사용하여 관찰한 것이다. 이중도약과제는 도약(saccadic)안구운동의 오차를 유발시키는 실험기법으로, 두개의 시각자극을 하나씩 연속적으로 보여주되, 두번째 자극은 안구운동이 일어나는 도중에 제시하는 것으로서, 인위적으로 왜곡된 공간에 대한 피험자의 공간적응을 관찰하는데 사용되었다. 이 과제는 다시 자극의 이차도약 방향에 따라 축소감 조건과 확장감 조건으로 나뉘었고, 머리운동의 역할을 판별하기 위해 머리를 고정한 조건과 머리를 자유롭게한 조건으로 분류되었다. 그 결과 머리가 고정된 상태에서는 축소감 조건에 대한 적응이 확장감 조건에서보다 더 빨리 일어나고, 그 적응후의 시선이동의 변화량에서도 축소감 조건이 더 크게 나타났다. 또한 머리를 자유롭게 할 공간 지각의 정확성이 증가하며, 축소감과 확장감 경험속도의 차이가 약 49.2%까지 해소되었으나, 여전히 축소감의 경험이 더 잘 일어났다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.1
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• pp.48-53
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• 2005

The purpose of this investigation is to explore the possibility of using artificial mechanical means for excitation of shear layers with application in swirling jet mixing enhancement. For this purpose, a mechanical excitation device was designed and fabricated. The major system components consist of two subsonic nozzles, one swirl generator, and the excitation device. The experiments were carried out at various helical excitation modes; i.e., m=+0, m=$\pm$1, m=$\pm$2, m=$\pm$3, and m=$\pm$4. Axial mean velocity measurements were made with plane and helical wave excitation using a hot-wire anemometer. The results are compared with the baseline (plane-wave excitation) at various helical modes. The acquired data is presented in 3-D mesh plots and 2-D contour plots. It was observed that new device was effective in excitation of the helical instability waves and resulting in mixing enhancement of the swirling jet.

• Journal of Biomedical Engineering Research
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• v.22 no.6
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• pp.487-496
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• 2001

In this study, a galvanic stimulator providing bipolar mode controlled by a PIC(peripheral interface controller) was constructed to evaluate vestibular function The maximum load and maximum current intensity of the constant current source were 3$k\Omega$ and 5mA. respectively. and it could Produce DC, sine wavers. or Pulse waves. Eve movements of 20 normal subjects by galvanic stimulation were analyzed using a commercial videooculogragh. During stimulating with DC for 30 sec. we recorded the response of eye movement with current intensity of 0.75. 1 2, and 3 mA. Nystagmus occurred to all the subjects when the galvanic stimulus intensity was larger than 2 mA. Average SPV(slow Phase eye movement velocity) and the number of nystagmus increased from 7.1 to 4.8 deg/sec and from 17 to 48, respectively, when the stimulus current increased from 0.75 to 3 mA. All the fast eye movement of the nystagmus were the direction of the negative electrode. The asymmetry which means the difference between right- and left-eye movements decreased when the stimulus intensity increased. It is expected that this study would be useful in evaluating vestibular function and in studying basic Physiology mechanism of vestibular ocular reflex by galvanic stimulus .

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.6
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• pp.606-615
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• 2003

This study examined the effects of exposure to the electromagnetic field emitted by mobile phone on human cognitive function. Total volunteers were twenty and volunteers were separated in two groups. One is teenager group, and the other is adult group. Test was performed in the counterbalanced order(sham-real, real-sham). Subject remained blind to mobile phone status during the exam. The result showed that the exposure to the electromagnetic field significantly speeded up response time fur teenager group. This results suggest that exposure to the electromagnetic field emitted by cellular phones may have a mild facilitating effect on cognitive function in teenager group.

• Korean Chemical Engineering Research
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• v.45 no.3
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• pp.304-309
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• 2007

In this study, the "Multi Well Plate-type cell Apparatus" was designed and setup for performing the producing experiments of methane hydrate by depressurization, heat stimulating methods. In order to characterizing the producing mechanism of hydrate through porous materials, the experiments for various producing methods have been conducted with the aid of the apparatus which has high permeability. In the experimental result of depressurization method, the pressure is temporarily increased unlikely conventional gas reservoir due to the sourcing effect of hydrate dissociation in the pore. Meanwhile, the temperature is decreased because of the endothermic reaction while hydrate is dissociated. In the experimental results of heat stimulating method, the dissociation in depressurization method is more slowly processed than that in thermal method, and hence, its gas production is lower. In the case of production right after heating, hydrate is dissociated only near injecting point and the permeability becomes greater at that area only. It infers that the more gas is produced during relatively earlier producing period. Since then, the hydrate is more slowly dissociated than the case of production after heating and soaking. This time, the performances of pressure and production obtained by thermal method have been analyzed in order to investigate the effect of soaking time on gas recovery. As a result, the gas recoveries in the case of 2 min and 4 min soaking are higher than case in 6 min soaking. This is reason that hydrate is reformed due to the decrease of temperature. It is expected that the experimental results obtained in this work may be more clearly explained by utilizing the lower permeable porous system with the greater hydrate saturation.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2000.04a
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• pp.67-70
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• 2000

본 논문은 음악 리듬의 속도의 변화가 작업자에게 미치는 영향을 평가하기 위하여 음악의 리듬의 속도를 다섯 단계로 변화시키면서 평가하였다. 평가를 위하여 미리 제작된 MIDI 음악을 들려주면서 피험자가 연산작업을 수행하는 동안의 오답 발생률과 연산반응시간과 뇌파 등 5종류의 생리신호를 측정하였다. 측정 데이터를 분석한 결과 자극음의 속도가 증가할수록 작업자의 오답률이 높아지고 연산 반응 시간이 길어져 작업능률이 저하됨을 관찰할 수가 있었다. 특히 리듬의 특정 속도 ♩=160(160/min)에서 ♩=200(200/min)보다 오답률이 높고 반응시간이 길어지므로 작업에 적합한 리듬의 속도가 존재함을 알 수 있었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.1
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• pp.615-621
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• 2018

To enhance the energy saving and comfort of indoors, this study performed a stimulation of sound fluctuation, color temperature, and aroma. The experiment with EEG, HRV, and Vibra images was conducted in an environmental test room with a temperature of $25[^{\circ}C]$, relative humidity of 50[RH%], air current speed of 0.002[m/s], and illuminance of 1000[lux]. The stimulation experiment set up different sensory stimulation conditions, such as before exposure, single-sensory stimulation of fluctuation a=1.106 jazz music, single-sensory stimulation of RED color lighting, single-sensory stimulation of scent aroma, and multi-sensory stimulation of fluctuation a=1.106 jazz music, RED color lighting, and scent aroma. After the multi-sensory stimulation of fluctuation a=1.106 jazz music, RED color lighting and scent aroma, the capacity for work and attention were increased, and the stress index and fatigue degree were decreased. In addition, multi-sensory stimulation of fluctuation a=1.106 jazz music, RED color lighting, and scent aroma were effective in maintaining a stable heart and health. In addition, the Vibra image appeared to decrease tension/anxiety and stress. The multi-sensory stimulation of fluctuation a=1.106 jazz music, RED color lighting, and scent aroma help increase the Neuro-energy more than that by no exposure and single-sensory stimulation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3579-3586
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• 2015

In this study, EEG, HRV, and Vibra image were compared and analyzed in the environmental test room due to stimulation of aroma and color temperature. The condition of the environmental test room was in temperature $25[^{\circ}C]$, relative humidity 50[RH%], air current speed 0.02[m/s] and illuminance 1000[lux] with setting up different sensory stimulation condition which are before exposure, single-sensory stimulation of Jasmine scent, single-sensory stimulation of RED color lighting, and multi-sensory stimulation of Jasmine scent and RED color lighting. The result of this study, at multi-sensory stimulation of Jasmine scent and RED color lighting, relative $S{\alpha}$ wave, SEF50, $SMR/{\theta}$ and SDNN were revitalized, and both sides ${\alpha}$ wave asymmetry index, stress index, fatigue degree, and HRT were decreased. Also, Viba image of tension/anxiety and stress were declined. Therefore multi-sensory stimulation of Jasmine scent and RED color lighting effects to increase the Neuro-energy like amenity, productivity of work efficiency, and concentration.